The field of the disclosure relates generally to composite repair verification, and more specifically, to methods and systems for non-destructive composite evaluation and repair verification.
With the increased usage of composites for aircraft structures, obtaining rapid, low-cost, yet high resolution non-destructive evaluation (NDE) data on in-service composite aircraft has become more important, and yet still remains a need within the aerospace industry. While damage assessment may be done with a lower resolution scanner or handheld single transducer system, composite repair verification requires high spatial resolution to quantify porosity. Currently only scanned pulse echo ultrasound is capable of providing the zoned porosity measurements required for validating composite scarfed and bonded repairs. Currently validation of such repairs can only be performed using expensive equipment.
One existing validation tool includes a handheld ultrasonic transducer (UT) system with individual transducers or phased array systems. However, handheld scanning is very slow and cannot produce the images required in many cases, for example, the measurement of porosity that is utilized in composite repairs. Moreover, such phased array UT systems are very expensive and somewhat complex.
Another validation tool is a mobile automated scanner (MAUS) which is a system that attaches to the structure being validated, such an aircraft, and scans individual UT probes or arrays. The MAUS scanner is also expensive, complicated to operate (using it requires specialized skills), and further requires two people to attach and run. As such, few potential users can afford it, and it is limited to minimally contoured structures because of the design of the flexible track and scanner arm, for example, it cannot do leading edges, or corners of structures having a radius.
A rapid scan tool is a variant of the phased array ultrasonic process, and uses a wheel probe, containing an array transducer, which is passed across the surface of a component generating a picture of the structure under test. While the rapid scan tool collects image data quickly, the cost and complexity of the system limit broad usage. Further, it is not designed for highly contoured surfaces, and has no three-dimensional imaging capability.
Other validation tools include a positional encoder capability to create scanned images and incorporate a manually manipulated radius-angle scanner arm. The scanner base incorporates encoders that register the position and orientation of the probe head. Systems with positional encoders are slow, and do not have the spatial resolution required for composite repair validation and porosity measurement. Further, they do not include a three-dimensional imaging capability.
The freehand area scanning tool (FAST) utilizes recent advances in the precision of IMU (Inertial Measurement Unit) devices and arrays to permit free-hand scanning for rapid NDE data collection. The FAST applies to many inspection applications, but the IMUs it is based upon do not currently have the spatial resolution for zoned porosity measurements in composite repairs.